Type I and Type II isoenzymes of cyclic AMP-dependent protein kinase would be purified from bovine carotid artery. Use of 8-aminohexyl ATP-Sepharose 4B along with the most commonly used purification procedures will be employed to achieve this goal. Various physical, chemical, and regulatory properties of these two isoenzymes will be determined. In order to understand the molecular mechanism of the enzyme reaction and to examine how subunit interactions influence the protein kinase activity, purification of the subunit components (i.e., the regulatory and the catalytic subunits) of these isoenzymes will be carried out.